1. Field of the Invention
The present invention relates to a moisturizer containing a particular acylproline or a salt thereof, and a composition containing (A) the acylproline or a salt thereof and (B) bisphosphonate. Also, it relates to a cosmetic agent containing the above-mentioned moisturizer or composition.
2. Discussion of the Background
Skin's moisture level deeply relates to the maintenance of youthful skin. Therefore, various moisturizers are generally added to cosmetics to keep the skin's moisture level. Moisturizers are required to have hygroscopicity and retain water. Various moisturizers such as betaine, sodium lactate, pyrrolidonecarboxylic acid, glycerol, sorbitol and the like have been used heretofore (non-patent document 1). However, since none of them have both the hygroscopicity and water retention ability, they cannot necessarily provide a cosmetic agent that sufficiently maintains the skin's moisture level.
Moreover, 1,3-butyleneglycol is a material that potentiates a preservation effect while being effective as a moisturizer, and can also be an auxiliary for the preservative (non-patent document 2). Such multi-functional material is highly useful. However, the moisturizing effect and preservative effect of 1,3-butylene glycol are not sufficient, and a material having a higher effect is earnestly desired.